Aircraft utilize lever latches in many applications for retaining doors and access panels in their closed position. Latches utilized on the exterior of aircraft have aerodynamic requirements that necessitate flush mounting within the aircraft outer skin. To achieve this, the latching member or bolt is held within a recessed channel housing when it is in its closed condition, hence the name “channel latch.”
Because of safety concerns and the serious nature of the equipment used in conjunction with these latches, there are requirements for ensuring that the latch bolt be locked down so that it does not inadvertently open due to vibration or shock that aircraft often experience. There is a further need for easily verifying that the lock-down mechanism is engaged. As an added measure of safety there is a need for a locking mechanism which requires a special tool to operate and which is vibration and shock avoidant.
There have been attempts to meet these needs in the art such as the latch described in U.S. Pat. No. 8,356,844 assigned to Avibank Manufacturing, Inc. entitled, “Flush Latch With Positive Lock”. This patent describes an aircraft latch with a locking mechanism; however, the means to retain the device in the locked position is a spring which is subject to failure or could be overcome by severe shock. Also, because the locking means is biased in the locked position, it can become damaged if the latch is inadvertently closed. Furthermore the device disclosed in this document has a great multiplicity of parts with such complexity that could adversely affect reliability and maintenance.
There is therefore still a need in the art for a locking latch which provides a locking mechanism that avoids inadvertent damage and which provides a positive secondary locking means that cannot be overcome by shock or vibration. It is further desired that these needs be met with a device which is compact, light weight and which has a limited number of parts.